STAT3 activation by catalpol promotes osteogenesis-angiogenesis coupling, thus accelerating osteoporotic bone repair

Accelerated differentiation of photothermal effect-induced mesenchymal stem cells regulated by activating HSP90-autophagy boosts wound repair

Mesenchymal Stem Cells (MSC) have the potential for pluripotent differentiation, transformation into stromal cells, and release of various cytokines to accelerate tissue healing as well as fight against inflammatory response. However, the differentiation and maturation of MSC require considerable time, which limits their clinical application. To tackle this difficulty, we herein propose a strategy of "selective accelerated activation of MSC by photothermal effect (PTE)" based on our previous work of "laser-controlled platelet activation". In vitro experiments presented that a photothermal agent (Indocyanine green, ICG) could be loaded by bone marrow-derived MSC (BMSC), which facilitated temperature increase under laser irradiation, leading to the speed differentiation and maturity of BMSC. Further findings revealed that PTE prevented BMSC from oxidative stress, thereby reducing inflammation and apoptosis. The ICG-loaded BMSC, which mixed with hydrogel, was further covered on the acute wounds in rats, promoting wound healing and blood vessel regeneration under laser irradiation. In-depth RNA-sequencing results indicated that PTE treatment led to the differentially expressed genes (DEGs) enriched in autophagy and PI3K signaling pathways, as confirmed by the increased expression of autophagy-associated biomarkers and observed autophagosome in BMSC. Furthermore, the HSP90 was activated in response to the PTE, which inhibited PI3K signaling. Finally, the silence of HSP90 abolished PTE-driven PI3K blockage, autophagy, and differentiation of BMSC. To summarize, PTE could facilitate the differentiation of MSC by triggering HSP90-mediated autophagy, which provides a novel approach for controlled MSC differentiation and the potential application of MSC cytopharmaceutics in wound repair.

Exosomal miR-137-3p targets UBE3C to activate STAT3, promoting migration and differentiation into endometrial epithelial cell of human umbilical cord mesenchymal stem cells under hypoxia

BACKGROUND

Thin endometrium, leading cause of recurrent implantation failure and infertility, has been found to respond to exosomes.

AIM

To investigate the efficacy of exosomes in addressing the issue of thin endometrium.

METHODS

RNA sequencing and reverse transcription-quantitative polymerase chain reaction were employed to identify differentially expressed microRNAs (miRNAs) in human umbilical cord mesenchymal stem cell (hucMSC) treated with exosomes enriched with endometrial cell-derived components. Additionally, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were conducted to highlight significant enrichment in specific biological pathways, molecular functions, and cellular components. Transwell and wound healing assays were performed to assess migratory potential, and western blotting was detected protein level.

RESULTS

A total of 53 differentially expressed miRNAs were identified in hucMSC treated with exosomes enriched with endometrial cell-derived components, comprising 27 upregulated and 26 downregulated miRNAs, which includes miR-137-3p. Enhanced migratory potential was observed in the Transwell and wound healing assays, and western blotting confirmed the epithelial differentiation of hucMSC and the increased p-signal transducer and activator of transcription 3. These effects were attributed to the upregulation of miR-137-3p.

CONCLUSION

miR-137-3p in exosomes from hypoxia-affected endometrial epithelial cell stimulates the signal transducer and activator of transcription 3 signaling pathway, enhancing the migration and differentiation of hucMSC into endometrial epithelial cell.

Utilizing bioinformatics to identify biomarkers and analyze their expression in relation to immune cell ratios in femoral head necrosis

Background

Necrosis of the Femoral Head (NFH) represents a challenging orthopedic condition, characterized by elusive early detection and rapid progression, predominantly in the middle-aged demographic. Current research on the pathophysiological and immunoregulatory mechanisms underpinning immune cell infiltration in NFH is sparse. This study employs bioinformatics analysis of publicly available RNA sequencing databases to elucidate the pivotal molecules and pathways implicated in NFH progression.

Methods

The NFH-related dataset GSE123568 was obtained from the Gene Expression Omnibus (GEO). Subsequently, CIBERSORT was utilized to assess the proportion and distribution of immune cell types, followed by the identification of critical Hub immune cells using LASSO and RFE algorithms. The dataset GSE123568 was then explored to identify significantly differentially expressed genes (DEGs). These genes were further refined by intersecting with death-associated genes reported in existing literature. GO and KEGG pathway enrichment analyses were conducted to elucidate their underlying molecular mechanism. A protein-protein interaction (PPI) network was constructed using the STRING database and visualized via Cytoscape. Hub genes were identified using the CytoHubba plugin, followed by enrichment analysis, and their expression levels were evaluated using the ROC curve. In addition, we performed expression data visualization and ROC curve analysis on the external dataset GSE74089 to further evaluate the discriminative power of the hub genes. Moreover, the study analyzed the correlation between the identified hub genes and Hub immune cells. Finally, we verified the hub genes utilizing real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry.

Results

Four types of immune cells (Neutrophil, Mast cell resting, Myeloid dendritic cell activated, Macrophage M0) were identified. Fourteen pivotal genes (BCL2L1, BIRC2, NFKBIA, XIAP, CFLAR, AKT1, BIRC3, IKBKB, RIPK1, CASP8, TNFRSF1A, IL1B, CASP1, STAT3) were identified, and the findings were validated using the external dataset GSE74089. Among these, STAT3 exhibited the most pronounced positive correlation with neutrophils (r = 0.6804, p = 3.525e-05). Conversely, XIAP displayed the most significant negative correlation with Myeloid dendritic cell activated (r = -0.3610, p = 0.04003). In experiments, the experimental outcomes for five hub genes (CASP8, TNFRSF1A, AKT1, XIAP and STAT3) were congruent with the results obtained from bioinformatics analysis.

Conclusion

Our study identified CASP8, TNFRSF1A, AKT1, XIAP, STAT3 and BCL2L1 as potential biomarkers for NFH patients and elucidated the immune cell types with the strongest association to these markers. These insights may be crucial for the early diagnosis, understanding of the pathophysiological mechanisms, and the development of treatment strategies for NFH.

Oxalate stimulates macrophage secretion of prostaglandin E2 to promote renal tubular epithelial cell osteogenesis

Osteogenesis of renal tubular epithelial cells (RTEC) is an important trigger for calcium oxalate (CaOx) kidney stone formation, but whether macrophages are involved in RTEC osteogenesis is unclear. The purpose of this study was to investigate the role and mechanism of macrophages in CaOx kidney stones on RTEC osteogenesis. Oxalate or ethylene glycol was used to construct in vitro and in vivo CaOx kidney stone models, respectively. Macrophage-derived conditioned medium was used to induce osteogenesis in HK-2 cells, and genetic controls and pharmacological interventions were used to investigate the underlying mechanism. The results demonstrated that macrophage-conditioned medium under oxalate intervention facilitated the increase of alkaline phosphatase and calcium salts as well as the upregulation of osteogenic marker genes (BMP2 and RUNX2) expression in HK-2 cells. On the one hand, the knockdown of the JAK2 gene in HK-2 cells reverses the role of macrophage-derived conditioned medium in promoting osteogenesis in HK-2 cells. On the other hand, inhibition of prostaglandin E2 (PGE2) generation in macrophages reverses osteogenesis in HK-2 cells. Moreover, inhibition of PGE2 generation would cure ethylene glycol-induced renal injury and calcium salt deposition, as well as osteogenesis of RTEC. This study illustrates that in the presence of oxalate, macrophages secret PGE2 to activate JAK2/STAT3 signaling in RTEC, which could trigger osteogenesis. It provides new insights into the mechanism of CaOx kidney stone formation.

Albiflorin improves osteoporotic bone regeneration by promoting osteogenesis-angiogenesis coupling of bone marrow mesenchymal stem cells

Albiflorin (ALB) has been shown to promote osteogenesis, however, its effect on angiogenesis still remains unclear. This research aimed to explore the effect of ALB on angiogenesis and bone regeneration under osteoporotic conditions. The pro-osteogenesis capacity of ALB was assessed by osteogenic differentiation assays. Subsequent research examined the effect of ALB on angiogenesis. After revealing the pro-angiogenesis capacity of ALB, we explored the relationship between the pro-osteogenesis capacity and the pro-angiogenesis capacity of ALB by angiogenesis-related assays. Whereafter, the osteoporotic bone defect rat model was constructed to explore the effect of ALB on osteoporotic bone regeneration. Our research found that ALB promoted osteogenesis of bone marrow mesenchymal stem cells (BMSCs) and enhanced the expression of angiogenesis-specific markers, but it couldn't promote angiogenesis of human umbilical vein endothelial cells (HUVECs) directly. Further research revealed that ALB enhanced HUVECs migration and tube formation when the cells cultured in BMSCs-conditioned medium. Subsequently, it is observed that ALB facilitated bone regeneration under osteoporotic conditions by promoting osteogenesis and the formation of CD31hiEMCNhi type H-positive vessels. To sum up, this research indicated that ALB could improve osteoporotic bone regeneration by promoting osteogenesis-angiogenesis coupling of BMSCs, which provided a novel perspective for improving osteoporotic bone regeneration.

LINC00968 accelerates osteogenic differentiation of bone marrow mesenchymal stem cells via the miR-17-5p/STAT3 axis

BACKGROUND

BMSCs with robust osteogenic differentiation capacity can participate in the repair of osteoporotic (OP) bone. Long non-coding RNAs (LncRNAs) serve as crucial regulators of osteogenic differentiation. This study aims to investigate the clinical implications of LINC00968 in OP and elucidate its molecular mechanisms.

METHODS

Patients with OP and controls without OP were enrolled. RT-qPCR was utilized the quantify the levels of LINC00968, miR-17-5p, STAT3, and osteogenic differentiation markers. ROC curve was conducted to evaluate the diagnostic significance. Osteogenic differentiation medium (OM) induced hBMSCs. Flow cytometry was used to examine apoptosis. DLR and RIP assay were performed to validate target binding.

RESULTS

LINC00968 was notably decreased in the serum and bone tissue of patients with OP, whereas it was markedly elevated during osteogenic differentiation of hBMSCs. LINC00968 has 78.65% sensitivity and 71.95% specificity in identifying OP patients from controls. Silencing of LINC00968 sharply diminished ALP activity and osteogenic differentiation markers levels while promoting apoptosis in hBMSCs under OM induction. However, this reduction was notably reversed by the administration of a miR-17-5p inhibitor. Molecularly, miR-17-5p directly targets LINC00968 and STAT3.

CONCLUSIONS

Our results indicate that LINC00968 downregulation is a diagnostic biomarker for OP, facilitating osteogenic differentiation and inhibiting apoptosis via miR-17-5p/STAT3 axis, suggesting a new therapeutic target for OP progression.

Recent advances in the multifaceted mechanisms of catalpol in treating osteoporosis

Catalpol (CAT) is a landmark active ingredient in traditional Chinese medicine Rehmannia (TCT), also known as dehydroxybenzoate catalpone, which is a kind of iridoid terpene glycoside with strong antioxidant, anti-inflammatory, antitumor and other biological activities. It can exert its anti-disease effect in a variety of ways. For some patients with chronic diseases, the application of azalea alcohol in rehmannia may bring more comprehensive and long-lasting efficacy. Studies have shown that the anti-disease effect of catalpol in osteoporosis (OP) is mainly achieved through various pathways such as Wnt/β-catenin signaling pathways to promote osteogenic differentiation, and RANKL/RANK and other signaling pathways to inhibit osteoclastic differentiation. At present, there is a slight lack of analysis of the mechanism of action of catalpa alcohol in the treatment of osteoporosis, so this study comprehensively searched the literature on the mechanism of action of catalpa alcohol in the treatment of osteoporosis in various databases, and reviewed the research progress of its role and mechanism, to provide reference and theoretical basis for the further development and application of catalpol.

Versatile hydrogels prepared by microfluidics technology for bone tissue engineering applications

Bone defects are a prevalent issue resulting from various factors, such as trauma, degenerative diseases, congenital disabilities, and the surgical removal of tumors. Current methods for bone regeneration have limitations. In this context, the fusion of tissue engineering and microfluidics has emerged as a promising strategy in the field of bone regeneration. This study describes the classification of microfluidic devices based on the nature of flow and channel type, as well as the materials and techniques required. An overview of microfluidic methods used to prepare hydrogels and the advantages of using these hydrogels in bone tissue engineering (BTE) combining several basic elements of BTE to highlight its advantages is provided. Furthermore, this work emphasizes the benefits of using hydrogels prepared via microfluidics over conventional hydrogels in BTE because of their controlled release of cargo, they can be used for in situ injection, simplify the steps of single-cell encapsulation and have the advantages of high-throughput and precise preparation. Additionally, organ-on-a-chip models fabricated via microfluidics offer a platform for studying cell and tissue behaviors in an authentic and dynamic environment. Moreover, microfluidic devices can be utilized for noninvasive diagnosis and therapy. Finally, this paper summarizes the preclinical and clinical applications of hydrogels prepared via microfluidics for bone regeneration by focusing on their current developmental status, limitations associated with their application, and future challenges, which underscore their potential impacts on advancing regenerative medicine practices.

Network Pharmacology and Experimental Validation of the Therapeutic Effect of Baji Capsule on LPS-Induced Osteoporosis

Purpose

Osteoporosis is a common skeletal disease characterized by impaired bone microarchitecture, decreased bone mineral density and increased bone fragility, leading to a heavy physical and economic burden due to its greatly increased risk of fracture. Baji capsule is a proprietary medicine that can treat menstrual disorders and postmenopausal osteoporosis. However, the efficacy of Baji capsule has not been reported for osteoporosis caused by oxidative stress and inflammation. Therefore, the aim of this study was to evaluate whether Baji capsule has a therapeutic effect on lipopolysaccharide (LPS)-induced inflammatory osteoporosis and to explore the underlying mechanisms through network pharmacology.

Patients and Methods

Osteoporosis model in ICR mice induced with LPS. Mice were treated with vitamin E (100mg/kg), PBS, high-dose Baji capsule (810mg/kg) and low-dose Baji capsule (90mg/kg), respectively. The therapeutic effect of Baji capsule was evaluated by high-resolution micro-computed tomography (Micro-CT) and tissue section staining, serum inflammatory factor levels were assessed by ELISA, serum oxidative stress-related marker levels were determined by kits, and finally the mechanism was explored by network pharmacology and then verified by immunohistochemistry.

Results

Micro-CT results showed that Baji capsule attenuated LPS-induced inflammatory bone loss.Baji capsule also reduced serum inflammatory factor levels and oxygen free radical production. Target screening by network pharmacology yielded a total of 236 active ingredients of Baji capsule, as well as 278 common targets after taking the intersection of Baji capsule active ingredient targets and osteoporosis disease-related targets.

Conclusion

Baji capsule can treat osteoporosis by reducing inflammation and oxidative stress. The therapeutic effects of Baji capsule were shown to be multi-targeted and multi-pathway through network pharmacology. In the future, its anti-inflammatory and antioxidant properties can be utilized to further explore its therapeutic effects on inflammatory diseases, as well as a prospective study for the clinical treatment of osteoporosis.

Sarsasapogenin stimulates angiogenesis and osteogenesis coupling to treat estrogen deficiency-induced osteoporosis by activating the GPX4/SLIT3/ROBO1 axis

BACKGROUND

Promoting the coupling of osteogenesis and angiogenesis is a crucial strategy for the treatment of postmenopausal osteoporosis (PMOP). Estrogen deficiency induces ferroptosis, which is closely associated with the pathophysiology of PMOP. Sarsasapogenin (SAR) is a natural sapogenin with anti-oxidative effects. However, it is unclear whether SAR has a protective role against the impaired osteogenesis and angiogenesis coupling in PMOP. In this study, we evaluated the efficacy of SAR in estrogen deficiency-induced osteoporosis and explored the underlying mechanisms.

METHODS

Bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) were utilized to assess the in vitro effects of SAR on the coupling of osteogenesis and angiogenesis. In vivo experiments involved bilateral ovariectomy (OVX)-induced osteoporosis in mice and glutathione peroxidase 4 (GPX4)-knockout (KO) mice. Mice were orally administered SAR (5 or 10 mg/kg/d) for a duration of 12 weeks. The direct target of SAR was investigated through molecular docking, a cellular thermal shift assay, and surface plasmon resonance. Additionally, RNA sequencing was employed to elucidate the underlying mechanisms.

RESULTS

SAR treatment improved cell viability and osteogenic differentiation while inhibiting ferroptosis in iron dextran-induced BMSCs. Furthermore, SAR enhanced the production of slit guidance ligand 3 (SLIT3) in these cells, which stimulated angiogenesis by activating its receptor, roundabout human homolog 1 (ROBO1), in HUVECs. An in vitro model of ferroptosis induced by erastin demonstrated that SAR promoted the coupling of osteogenesis and angiogenesis by upregulating the BMSCs-SLIT3/HUVECs-ROBO1 axis. Activation of GPX4 was identified as a contributing factor to the effects of SAR on this coupling. Transfection of GPX4 small interfering RNA (siRNA) in BMSCs negated the impact of SAR on the BMSCs-SLIT3/HUVECs-ROBO1 axis. Additionally, SAR was found to directly interact with GPX4, enhancing protein stability, with an equilibrium dissociation constant of 44.6 μM. Notably, SAR did not increase SLIT3, ROBO1, or indicators of osteogenesis or angiogenesis in GPX4-KO mice.

CONCLUSIONS

These findings underscore the significance of restoring the GPX4/SLIT3/ROBO1 axis in promoting the coupling of angiogenesis and osteogenesis. SAR mitigates PMOP, in part, by activating the BMSCs-SLIT3/HUVECs-ROBO1 axis, with GPX4 serving as an upstream signaling modulator responsible for SLIT3 production. Our observations provide experimental evidence supporting the clinical application of SAR in the treatment of PMOP.

Polydatin accelerates osteoporotic bone repair by inducing the osteogenesis-angiogenesis coupling of bone marrow mesenchymal stem cells via the PI3K/AKT/GSK-3β/β-catenin pathway

BACKGROUND

Polydatin (POL), a natural stilbenoid, has multiple pharmacological activities. However, its effect on osteoporotic bone defects has not yet been examined. This study was designed to explore the unknown role of POL on osteoporotic bone repair.

METHODS

The effect of POL on osteogenesis and angiogenesis were investigated firstly. Then a series of angiogenesis-related assays were carried out to explore the relationship between osteogenesis and angiogenesis of POL, and the underlying mechanism was further explored. Whereafter, ovariectomy-induced osteoporosis rats with bone defect were treated with POL or placebo, the imageological and histological examinations were conducted to assess the effect of POL on osteoporotic bone repair.

RESULTS

The moderate concentrations (1 μM and 10 μM) of POL enhanced the osteogenesis of bone marrow mesenchymal stem cells (BMSCs) and elevated the expression of angiogenic-specific markers. Further research found that POL-induced human umbilical vein endothelial cells migration and tube formation through the osteogenesis-angiogenesis coupling of BMSCs, and the POL-induced osteogenesis-angiogenesis coupling was reversed after co-cultured with LY294002. Mechanistically, this was conducted via activating PI3K/AKT/GSK-3β/β-catenin pathway. After that, using the osteoporotic bone defect rat model, the authors, observed that POL facilitated osteoporotic bone repair through enhancing osteogenesis and CD31 hi EMCN hi type H-positive vessels formation via the PI3K/AKT/GSK-3β/β-catenin pathway.

CONCLUSION

The data above indicated that POL could accelerate osteoporotic bone repair by inducing the osteogenesis-angiogenesis coupling of BMSCs via the PI3K/AKT/GSK-3β/β-catenin pathway, which provided new insight and strategy for osteoporotic bone repair.

Single-cell RNA transcriptomics reveals Du-Zhong-Wan promotes osteoporotic fracture healing via YAP/β-catenin/VEGF axis in BMSCs

BACKGROUND

Our previous study demonstrated that Du-Zhong-Wan (DZW) promoted osteoporotic fracture (OPF) healing by enhancing osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and angiogenesis of endothelial cells (ECs). However, the heterogeneity of BMSCs and ECs, as well as the specific molecular mechanism underlying these effects, still require further evaluation.

PURPOSE

The primary objective of this study was to elucidate the heterogeneity of BMSCs and ECs, as well as the cellular-level mechanism of DZW against OPF through single-cell RNA sequencing.

METHODS

In this study, we presented a single-cell atlas of mouse femoral callus, comparing samples with and without DZW treatment, utilizing single-cell RNA sequencing. Variable genes were identified using the FindVariableGenes (FVG) and principal component analysis (PCA) analysis. Additionally, uniform manifold approximation and projection (U-MAP) was employed to reduce and visualize the distinct subclusters. The CellPhoneDB2 method was employed to analyze intercellular communication and quantify the interaction between ligands and receptors within distinct cell clusters. The osteogenic differentiation capacity of BMSCs was assessed by micro-CT, alkaline phosphatase (ALP), and alizarin red S (ARS) assay. The scratch wound assay and tube formation assay were utilized to assess the angiogenic capabilities of ECs in vitro. Additionally, western blot and immunofluorescence experiments were utilized to elucidate the related protein expression.

RESULTS

Consistent with our previous studies, DZW obviously promoted osteoporotic fracture healing. Moreover, this study discovered 14 cell clusters at the femoral fracture callus, where the BMSCs most actively interacted with ECs, through single-cell sequencing. Notably, DZW significantly elevated the proportion of Lepr+ BMSCs and Podxl+ ECs subgroup, which were respectively considered essential cells for osteoblastogenesis and angiogenesis of arteriolar vessels. The increased proportion of Podxl+ ECs was partially attributed to vascular endothelial growth factor (VEGF), secreted by BMSCs, which were able to be reversed by YAP pharmacological inhibitor verteporfin. Furthermore, the western blot assay revealed elevated expression levels of YAP/β-catenin, VEGF, RUNX2, and OCN in BMSCs treated with DZW, which were counteracted by verteporfin.

CONCLUSION

The data above indicates that DZW elevates the proportion of LEPR+ BMSCs and Podxl+ ECs, therefore contributing for the osteogenic ability of BMSCs and BMSCs-mediated angiogenesis via activation of the YAP/β-catenin/VEGF axis, which provides novel potential targets and mechanism for DZW in treating OPF in sub-clusters and molecular level.

Catalpol Enhances Osteogenic Differentiation of Human Periodontal Stem Cells and Modulates Periodontal Tissue Remodeling in an Orthodontic Tooth Movement Rat Model

Purpose

This study examines the effects and mechanisms of catalpol (CAT) on the proliferation and osteogenic differentiation of cultured human periodontal ligament stem cells (hPDLSCs) in vitro and assesses the impact of CAT on periodontal remodeling in vivo using an orthodontic tooth movement (OTM) model in rats.

Methods

hPDLSCs were cultured in a laboratory setting, and their proliferation and osteogenic differentiation were assessed using the Cell-counting Kit-8 (CCK-8), Alizarin Red Staining (ARS), quantitative calcium assay, alkaline phosphatase (ALP) staining and activity assay, and immunofluorescence assay. Additionally, the expression of collagen type 1 (COL-1), ALP, and runt-related transcription factor-2 (RUNX-2) was evaluated through qRT-PCR and Western blot analysis. To verify the function of the estrogen receptor-α (ER-α)-mediated phosphatidylinositol-3-kinase-protein kinase B (PI3K/AKT) pathway in this mechanism, LY294002 (a PI3K signaling pathway inhibitor) and the ER-α specific inhibitor methyl-piperidine-pyrazole (MPP) were used. The osteogenic markers ER-α, AKT, and p-AKT (phosphoprotein kinase B) were identified through Western blot analysis. Eighteen male Sprague-Dawley rats were assigned to two groups randomly: a CAT group receiving CAT and a control group receiving an equivalent volume of saline. Micro-computed tomography (micro-CT) analysis was employed to evaluate tooth movement and changes in alveolar bone structure. Morphological changes in the periodontal tissues between the roots were investigated using hematoxylin and eosin (HE) staining and tartaric-resistant acid phosphatase (TRAP) staining. The expression of COL-1, RUNX-2, and nuclear factor-κB (NF-κB) ligand (RANKL) was assessed through immunohistochemical staining (IHC) to evaluate periodontal tissue remodeling. Tests were analyzed using GraphPad Prism 8 software. Differences among more than two groups were analyzed by one-way or two-way analysis of variance (ANOVA) followed by the Tukey's test. Values of p < 0.05 were regarded as statistically significant.

Results

In vitro experiments demonstrated that 10 μM CAT significantly promoted the proliferation, ALP activity, and calcium nodule formation of hPDLSCs, with a notable increase in the expression of COL-1, ALP, RUNX-2, ER-α, and p-AKT. The PI3K/AKT pathway was inhibited by LY294002, and further analysis using MPP suggested that ER-α mediated this effect. In vivo, experiments indicated that CAT enhanced the expression of COL-1 and RUNX-2 on the tension side of rat tooth roots, reduced the number of osteoclasts on the compression side, inhibited RANKL expression, and suppressed OTM.

Conclusion

CAT can promote hPDLSCs proliferation and osteogenic differentiation in vitro through the ER-α/PI3K/AKT pathway and enhance periodontal tissue remodeling in vivo using OTM models. These findings suggest the potential for the clinical application of catalpol in preventing relapse following OTM.

Single-cell sequencing reveals that specnuezhenide protects against osteoporosis via activation of METTL3 in LEPR+ BMSCs

BACKGROUND

Osteoporosis (OP) has garnered significant attention due to its substantial morbidity and mortality rates, imposing considerable health burdens on societies worldwide. However, the molecular mechanisms underlying osteoporosis pathogenesis remain largely elusive, and the available therapeutic interventions are limited. Therefore, there is an urgent need for innovative strategies in the treatment of osteoporosis.

PURPOSE

The primary objective of this study was to elucidate the molecular mechanisms underlying osteoporosis pathogenesis using single-cell RNA sequencing (scRNA-seq), thereby proposing novel therapeutic agents.

METHODS

The mice osteoporosis model was established through bilateral ovariectomy. Micro-computed tomography (μCT) and hematoxylin and eosin (H&E) staining were employed to assess the pathogenesis of osteoporosis. scRNA-seq was utilized to identify and analyze distinct molecular mechanisms and sub-clusters. Gradient dilution analysis was used to obtain specific sub-clusters, which were further validated by immunofluorescence staining and flow cytometry analysis. Molecular docking and cellular thermal shift assay (CETSA) were applied for screening potential agents in the TCMSPs database. Alkaline phosphatase (ALP) activity and alizarin red S (ARS) staining were performed to evaluate the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Osteogenic organoids analysis was employed to assess the proliferation and sphere-forming ability of BMSCs. Quantitative real-time PCR (qRT-PCR) and western blot analysis were conducted to investigate signaling pathways. Wound healing assay and tube formation analysis were employed to evaluate the angiogenesis of endothelial cells.

RESULTS

The scRNA-seq analysis revealed the crucial role of LEPR+ BMSCs in the pathogenesis of osteoporosis, which was confirmed by immunofluorescence staining of the epiphysis. Subsequently, the LEPR+ BMSCs were obtained by gradient dilution analysis and identified by immunofluorescence staining and flow cytometry. Accordingly, specnuezhenide (Spe) was screened and identified as a potential compound targeting METTL3 from the TCMSPs database. Spe promoted bone formation as evidenced by μ-CT, and H&E analysis. Additionally, Spe enhanced the osteogenic capacity of LEPR+ BMSCs through ALP and ARS assay. Notably, METTL3 pharmacological inhibitors S-Adenosylhomocysteine (SAH) attenuated the aforementioned osteo-protective effects of Spe. Particularly, Spe enhanced the LEPR+ BMSCs-dependent angiogenesis through the secretion of SLIT3, which was abolished by SAH in LEPR+ BMSCs.

CONCLUSION

Collectively, these findings suggest that Spe could enhance the osteogenic potential of LEPR+ BMSCs and promote LEPR+ BMSCs-dependent angiogenesis by activating METTL3 in LEPR+ BMSCs, indicating its potential as an ideal therapeutic agent for clinical treatment of osteoporosis.

In-silico analysis predicts disruption of normal angiogenesis as a causative factor in osteoporosis pathogenesis

Angiogenesis-osteogenesis coupling is critical for proper functioning and maintaining the health of bones. Any disruption in this coupling, associated with aging and disease, might lead to loss of bone mass. Osteoporosis (OP) is a debilitating bone metabolic disorder that affects the microarchitecture of bones, gradually leading to fracture. Computational analysis revealed that normal angiogenesis is disrupted during the progression of OP, especially postmenopausal osteoporosis (PMOP). The genes associated with OP and PMOP were retrieved from the DisGeNET database. Hub gene analysis and molecular pathway enrichment were performed via the Cytoscape plugins STRING, MCODE, CytoHubba, ClueGO and the web-based tool Enrichr. Twenty-eight (28) hub genes were identified, eight of which were transcription factors (HIF1A, JUN, TP53, ESR1, MYC, PPARG, RUNX2 and SOX9). Analysis of SNPs associated with hub genes via the gnomAD, I-Mutant2.0, MUpro, ConSurf and COACH servers revealed the substitution F201L in IL6 as the most deleterious. The IL6 protein was modeled in the SWISS-MODEL server and the substitution was analyzed via the YASARA FoldX plugin. A positive ΔΔG (1.936) of the F201L mutant indicates that the mutated structure is less stable than the wild-type structure is. Thirteen hub genes, including IL6 and the enriched molecular pathways were found to be profoundly involved in angiogenesis/endothelial function and immune signaling. Mechanical loading of bones through weight-bearing exercises can activate osteoblasts via mechanotransduction leading to increased bone formation. The present study suggests proper mechanical loading of bone as a preventive strategy for PMOP, by which angiogenesis and the immune status of the bone can be maintained. This in silico analysis could be used to understand the molecular etiology of OP and to develop novel therapeutic approaches.

Radix Rehmanniae Praeparata promoted zebrafish fin regeneration through aryl hydrocarbon receptor-dependent autophagy

HEADINGS ETHNOPHARMACOLOGICAL RELEVANCE

Rehmanniae Radix Praeparata (RRP), a staple in traditional Chinese medicine, is derived from Rehmannia glutinosa Libosch and is renowned for its wound-healing properties. Despite its clinical prevalence, the molecular mechanisms underlying RRP's wound-healing effects have not been fully elucidated.

AIM OF THE STUDY

This research endeavored to delineate the molecular and cellular mechanisms underlying the beneficial effects of RRP on wound healing, utilizing a zebrafish model.

MATERIALS AND METHODS

Zebrafish larvae at 3 days post-fertilization were amputated at the fin and subsequently treated with RRP. The pro-wound healing and regenerative effects of RRP were evaluated through morphological analysis, assessment of cell proliferation and apoptosis, Additionally, mechanistic insights were gained through a comprehensive approach encompassing network pharmacology analysis, cell tracing, RNA-sequencing, CRISPR/Cas9 gene editing, and pharmacological inhibition.

RESULTS

Our findings demonstrate that RRP significantly accelerates caudal fin regeneration in zebrafish following injury by suppressing cell apoptosis, promoting cell proliferation, and upregulating the expression of regenerative-related genes. Furthermore, RRP triggers autophagy signals during the regenerative process, which is attenuated by the autophagy inhibitor chloroquine (CQ). Notably, the administration of RRP enhances the expression of ahr1 and ahr2 in the regenerating fin. Genetic knockout of ahr1a, ahr1b, or ahr2 using CRISPR/Cas9, or pharmacological blockade of AHR signals with the antagonist CH-223191, diminishes the regenerative potential of RRP. Remarkably, zebrafish lacking ahr2 completely lose their fin regeneration ability. Additionally, inhibition of AHR signaling suppresses autophagy signaling during fin regeneration.

CONCLUSIONS

This study uncovers that RRP stimulates fin regeneration in zebrafish by inducing AHR signals and, at least partially, activating the autophagy process. These findings provide novel insights into the molecular mechanisms underlying the wound-healing effects of RRP and may pave the way for the development of novel therapeutic strategies.

Resveratrol reversed rosiglitazone administration induced bone loss in rats with type 2 diabetes mellitus

Rosiglitazone (RSG), as an insulin-sensitizing drug to treat type 2 diabetes mellitus (T2DM) is reported to decrease bone quality and increase bone fracture risk. The multiple off-target effects of Resveratrol (RSV), a natural specific agonist of Sirtuin1 (Sirt1) with pro-osteoblastogenesis and anti-adipogenesis effects, on bone loss in T2DM are still under discussion. In this study, successfully ovariectomized rats were fed with high-fat diet and STZ (HFD/STZ) to induced T2DM mice. RSV alone, RSG alone or co-administration of RSV and RSG were given orally to T2DM rats for 8 weeks to determine whether RSV administration had any prevention effect on T2DM osteoporosis. Bone mesenchymal stem cells (BMSCs) and bone marrow‑derived macrophages (BMMs) were cultured under high glucose condition and were induced to osteoblasts or adipocytes and osteoclasts, respectively. μCT and HE staining showed that in T2DM osteoporotic rats, RSV co-administration prevents RSG induced-bone loss. ELISA results confirmed that RSV suppressed osteoclast activity and promoted osteoblast activity in diabetic osteoporosis rats and RSG-administrated diabetic osteoporosis rats. In vitro study showed that RSV significantly reversed RSG induced inhibition on osteogenesis and promotion on adiopogenesis of BMSC under high glucose (HG). Moreover, RSV significantly reverse RSG induced osteoclast formation and mature under HG. Taken together, these findings uncover a previously unappreciated anti-osteoporosis effect of concomitant treatment with RSV in RSG-administrated diabetic rats, suggesting the clinical use of RSV as an adjuvant in the treatment of T2DM for preventing or reversing RSG administration-associated bone loss.

Osthole accelerates osteoporotic fracture healing by inducing the osteogenesis-angiogenesis coupling of BMSCs via the Wnt/β-catenin pathway

Osthole, a natural coumarin derivative, has been shown to have multiple pharmacological activities. However, its effect on osteoporotic fracture has not yet been examined. This research was designed to explore the unknown role and potential mechanism of osthole on osteoporotic fracture healing. We first evaluated the osteogenic and angiogenic abilities of osthole. Then angiogenesis-related assays were conducted to investigate the relationship between osteogenesis and angiogenesis, and further explore its molecular mechanism. After that, we established osteoporotic fracture model in ovariectomy-induced osteoporosis rats and treated the rats with osthole or placebo. Radiography, histomorphometry, histology, and sequential fluorescent labeling were used to evaluate the effect of osthole on osteoporotic fracture healing. In vitro research revealed that osthole promoted osteogenesis and up-regulated the expression of angiogenic-related markers. Further research found that osthole couldn't facilitate the angiogenesis of human umbilical vein endothelial cells in a direct manner, but it possessed the ability to induce the osteogenesis-angiogenesis coupling of bone marrow mesenchymal stem cells (BMSCs). Mechanistically, this was conducted through activating the Wnt/β-catenin pathway. Subsequently, using ovariectomy-induced osteoporosis tibia fracture rat model, we observed that osthole facilitated bone formation and CD31hiEMCNhi type H-positive capillary formation. Sequential fluorescent labeling confirmed that osthole could effectively accelerate bone formation in the fractured region. The data above indicated that osthole could accelerate osteoporotic fracture healing by inducing the osteogenesis-angiogenesis coupling of BMSCs via the Wnt/β-catenin pathway, which implied that osthole may be a potential drug for treating osteoporosis fracture.

A sponge-like nanofiber melatonin-loaded scaffold accelerates vascularized bone regeneration via improving mitochondrial energy metabolism

Electrospun nanofibers have been widely employed in bone tissue engineering for their ability to mimic the micro to nanometer scale network of the native bone extracellular matrix. However, the dense fibrous structure and limited mechanical support of these nanofibers pose challenges for the treatment of critical size bone defects. In this study, we propose a facile approach for creating a three-dimensional scaffold using interconnected electrospun nanofibers containing melatonin (Scaffold@MT). The hypothesis posited that the sponge-like Scaffold@MT could potentially enhance bone regeneration and angiogenesis by modulating mitochondrial energy metabolism. Melatonin-loaded gelatin and poly-lactic-acid nanofibers were fabricated using electrospinning, then fragmented into shorter fibers. The sponge-like Scaffold@MT was created through a process involving homogenization, low-temperature lyophilization, and chemical cross-linking, while maintaining the microstructure of the continuous nanofibers. The incorporation of short nanofibers led to a low release of melatonin and increased Young's modulus of the scaffold. Scaffold@MT demonstrated positive biocompatibility by promoting a 14.2 % increase in cell proliferation. In comparison to the control group, Scaffold@MT significantly enhanced matrix mineralization by 3.2-fold and upregulated the gene expression of osteoblast-specific markers, thereby facilitating osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs). Significantly, Scaffold@MT led to a marked enhancement in the mitochondrial energy function of BMMSCs, evidenced by elevated adenosine triphosphate (ATP) production, mitochondrial membrane potential, and protein expression of respiratory chain factors. Furthermore, Scaffold@MT promoted the migration of human umbilical vein endothelial cells (HUVECs) and increased tube formation by 1.3 times compared to the control group, accompanied by an increase in vascular endothelial growth factor (VEGFA) expression. The results of in vivo experiments indicate that the implantation of Scaffold@MT significantly improved vascularized bone regeneration in a distal femur defect in rats. Micro-computed tomography analysis conducted 8 weeks post-surgery revealed that Scaffold@MT led to optimal development of new bone microarchitecture. Histological and immunohistochemical analyses demonstrated that Scaffold@MT facilitated bone matrix deposition and new blood vessel formation at the defect site. Overall, the utilization of melatonin-loaded nanofiber sponges exhibits significant promise as a scaffold that promotes bone growth and angiogenesis, making it a viable option for the repair of critical-sized bone defects.

Coatless modification of 3D-printed Ti6Al4V implants through tailored Cu ion implantation combined with UV photofunctionalization to enhance cell attachment, osteogenesis and angiogenesis

The three-dimensional-printed Ti6Al4V implant (3DTi) has been widely accepted for the reconstruction of massive bone defects in orthopedics owing to several advantages, such as its tailored shape design, avoiding bone graft and superior bone-implant interlock. However, the osteoinduction activity of 3DTi is inadequate when applied clinically even though it exhibits osteoconduction. This study developes a comprehensive coatless strategy for the surface improvement of 3DTi through copper (Cu) ion implantation and ultraviolet (UV) photofunctionalization to enhance osteoinductivity. The newly constructed functional 3DTi (UV/Ti-Cu) achieved stable and controllable Cu doping, sustained Cu2+ releasing, and increased surface hydrophilicity. By performing cellular experiments, we determined that the safe dose range of Cu ion implantation was less than 5×1016 ions/cm2. The implanted Cu2+ enhanced the ALP activity and the apatite formation ability of bone marrow stromal cells (BMSCs) while slightly decreasing proliferation ability. When combined with UV photofunctionalization, cell adhesion and proliferation were significantly promoted and bone mineralization was further increased. Meanwhile, UV/Ti-Cu was conducive to the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro, theoretically facilitating vascular coupling osteogenesis. In conclusion, UV/Ti-Cu is a novel attempt to apply two coatless techniques for the surface modification of 3DTi. In addition, it is considered a potential bone substrate for repairing bone defects.

Icariin accelerates bone regeneration by inducing osteogenesis-angiogenesis coupling in rats with type 1 diabetes mellitus

BACKGROUND

Icariin (ICA), a natural flavonoid compound monomer, has multiple pharmacological activities. However, its effect on bone defect in the context of type 1 diabetes mellitus (T1DM) has not yet been examined.

AIM

To explore the role and potential mechanism of ICA on bone defect in the context of T1DM.

METHODS

The effects of ICA on osteogenesis and angiogenesis were evaluated by alkaline phosphatase staining, alizarin red S staining, quantitative real-time polymerase chain reaction, Western blot, and immunofluorescence. Angiogenesis-related assays were conducted to investigate the relationship between osteogenesis and angiogenesis. A bone defect model was established in T1DM rats. The model rats were then treated with ICA or placebo and micron-scale computed tomography, histomorphometry, histology, and sequential fluorescent labeling were used to evaluate the effect of ICA on bone formation in the defect area.

RESULTS

ICA promoted bone marrow mesenchymal stem cell (BMSC) proliferation and osteogenic differentiation. The ICA treated-BMSCs showed higher expression levels of osteogenesis-related markers (alkaline phosphatase and osteocalcin) and angiogenesis-related markers (vascular endothelial growth factor A and platelet endothelial cell adhesion molecule 1) compared to the untreated group. ICA was also found to induce osteogenesis-angiogenesis coupling of BMSCs. In the bone defect model T1DM rats, ICA facilitated bone formation and CD31hiEMCNhi type H-positive capillary formation. Lastly, ICA effectively accelerated the rate of bone formation in the defect area.

CONCLUSION

ICA was able to accelerate bone regeneration in a T1DM rat model by inducing osteogenesis-angiogenesis coupling of BMSCs.

ALPL regulates pro-angiogenic capacity of mesenchymal stem cells through ATP-P2X7 axis controlled exosomes secretion

BACKGROUND

Early-onset bone dysplasia is a common manifestation of hypophosphatasia (HPP), an autosomal inherited disease caused by ALPL mutation. ALPL ablation induces prototypical premature bone ageing characteristics, resulting in impaired osteogenic differentiation capacity of human bone marrow mesenchymal stem cells (hBMMSCs). As angiogenesis is tightly coupled with osteogenesis, it also plays a necessary role in sustaining bone homeostasis. We have previously observed a decrease in expression of angiogenesis marker gene CD31 in the metaphysis of long bone in Alpl+/- mice. However, the role of ALPL in regulation of angiogenesis in bone has remained largely unknown.

METHODS

Exosomes derived from Normal and HPP hBMMSCs were isolated and identified by ultracentrifugation, transmission electron microscopy, and nanoparticle size measurement. The effects of ALPL on the angiogenic capacity of hBMMSCs from HPP patients were assessed by immunofluorescence, tube formation, wound healing and migration assay. exo-ELISA and Western Blot were used to evaluate the exosomes secretion of hBMMSCs from HPP, and the protein expression of VEGF, PDGFBB, Angiostatin and Endostatin in exosomes respectively.

RESULTS

We verified that ALPL ablation resulted in impaired pro-angiogenic capacity of hBMMSCs, accounting for reduced migration and tube formation of human umbilical vein endothelial cells, as the quantities and proteins composition of exosomes varied with ALPL expression. Mechanistically, loss of function of ALPL enhanced ATP release. Additional ATP, in turn, led to markedly elevated level of ATP receptor P2X7, which consequently promoted exosomes secretion, resulting in a decreased capacity to promote angiogenesis. Conversely, inhibition of P2X7 increased the angiogenic induction capacity by preventing excessive release of anti-angiogenic exosomes in ALPL deficient-hBMMSCs.

CONCLUSION

The ALPL-ATP axis regulates the pro-angiogenic ability of hBMMSCs by controlling exosomes secretion through the P2X7 receptor. Thus, P2X7 may be proved as an effective therapeutic target for accelerating neovascularization in ALPL-deficient bone defects.

Catalpol promotes articular cartilage repair by enhancing the recruitment of endogenous mesenchymal stem cells

Articular cartilage defect is challenged by insufficient regenerative ability of cartilage. Catalpol (CA), the primary active component of Rehmanniae Radix, could exert protective effects against various diseases. However, the impact of CA on the treatment of articular cartilage injuries is still unclear. In this study, full-thickness articular cartilage defect was induced in a mouse model via surgery. The animals were intraperitoneally injected with CA for 4 or 8 weeks. According to the results of macroscopic observation, micro-computed tomography CT (μCT), histological and immunohistochemistry staining, CA treatment could promote mouse cartilage repair, resulting in cartilage regeneration, bone structure improvement and matrix anabolism. Specifically, an increase in the expression of CD90, the marker of mesenchymal stem cells (MSCs), in the cartilage was observed. In addition, we evaluated the migratory and chondrogenic effects of CA on MSCs. Different concentration of CA was added to C3H10 T1/2 cells. The results showed that CA enhanced cell migration and chondrogenesis without affecting proliferation. Collectively, our findings indicate that CA may be effective for the treatment of cartilage defects via stimulation of endogenous MSCs.

Zinc-based biomaterials for bone repair and regeneration: mechanism and applications

Zinc (Zn) is one of the most important trace elements in the human body and plays a key role in various physiological processes, especially in bone metabolism. Zn-containing materials have been reported to enhance bone repair through promoting cell proliferation, osteogenic activity, angiogenesis, and inhibiting osteoclast differentiation. Therefore, Zn-based biomaterials are potential substitutes for traditional bone grafts. In this review, the specific mechanisms of bone formation promotion by Zn-based biomaterials were discussed, and recent developments in their application in bone tissue engineering were summarized. Moreover, the challenges and perspectives of Zn-based biomaterials were concluded, revealing their attractive potential and development directions in the future.

Catalpol ameliorates dexamethasone-induced osteoporosis by promoting osteogenic differentiation of bone marrow mesenchymal stem cells via the activation of PKD1 promoter

OBJECTIVE

To investigate the effects of CA on glucocorticoid-induced osteoporosis (GIOP) and lucubrate the underlying mechanism of CA via the activation of polycystic kidney disease-1(PKD1) in bone marrow mesenchymal stem cells (BMSCs).

METHODS

In vivo, a GIOP model in mice treated with dexamethasone (Dex) was established. Biomechanical, micro-CT, immunofluorescence staining of OCN, ALP and PKD1 and others were severally determined. qRT-PCR and Western blot methods were adopted to elucidate the particular mechanisms of CA on GIOP. In addition, BMSCs cultured in vitro were also induced by Dex to verify the effects of CA. Finally, siRNA and luciferase activity assays were performed to confirm the mechanisms.

RESULTS

We found that CA could restore the destroyed bone microarchitecture and increase the bone mass in GIOP mice. CA could also upregulate PKD1 protein expression, reduce oxidative stress, and promote mRNA expression of bone formation-associated markers in GIOP mice. Furthermore, it was also observed that CA reduced oxidative stress and promoted osteogenic differentiation in Dex-induced BMSCs. Mechanically, CA could promote protein expression via increasing the activity of PKD1 promoter.

CONCLUSION

This study provides important evidences for CA in the further clinical treatment of GIOP, reveals the activation of PKD1 promoter as the underlying mechanism.

Endothelial Stat3 activation promotes osteoarthritis development

The mechanism of the balance between subchondral angiogenesis and articular damage within osteoarthritis (OA) progression remains a mystery. However, the lack of specific drugs leads to limited clinical treatment options for OA, frequently failing to prevent eventual joint destruction in patients. Increasing evidence suggests that subchondral bone angiogenesis precedes cartilage injury, while proliferating endothelial cells (ECs) induce abnormal bone formation. Signal transducer and activator of transcription 3 (Stat3) is triggered by multiple cytokines in the OA microenvironment. Here, we observed elevated Stat3 activation in subchondral bone H-type vessels. Endothelial Stat3 activation will lead to stronger cell proliferation, migration and angiogenesis by simulating ECs in OA. In contrast, either Stat3 activation inhibition or knockdown of Stat3 expression could relieve such alterations. More interestingly, blocking Stat3 in ECs alleviated angiogenesis-mediated osteogenic differentiation and chondrocyte lesions. Stat3 inhibitor reversed surgically induced subchondral bone H-type vessel hyperplasia in vivo, significantly downregulating vessel volume and vessel number. Due to the reduced angiogenesis, subchondral bone deterioration and cartilage loss were alleviated. Overall, our data suggest that endothelial Stat3 activation is an essential trigger for OA development. Therefore, targeted Stat3 blockade is a novel promising therapeutic regimen for OA.

Temporal transcriptome highlights the involvement of cytokine/JAK/STAT3 signaling pathway in the osteoinduction of BMSCs

BACKGROUND

Mesenchymal stem cells (MSCs)-based therapy offers an effective strategy for bone regeneration to solve the clinical orthopedic problems. However, the transcriptional regulation of multiple transitional stages of continuous osteogenesis from MSCs has not been fully characterized.

METHODS

Bone marrow mesenchymal stem cells (BMSCs) stimulated with osteogenic induction media were utilized to construct the in vitro osteogenic differentiation model. BMSCs were harvested after induction for 0, 7, 14 and 21 days, respectively, to perform the mRNA-sequencing (mRNA-Seq). The transcription factor networks and common molecules during the osteogenesis were revealed by using the temporal transcriptome. Further verification was performed by the quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence and Western blotting.

RESULTS

It showed that BMSCs could differentiate into osteogenic, and crucial regulator in the MAPK signaling pathway, the PPAR signaling pathway, the Toll-like receptor signaling and the Cytokine/JAK/STAT signaling pathway. PPI protein interaction analysis also suggested that three cytokines are involved in osteogenic differentiation as core genes, including leukemia inhibitory factor (LIF), interleukin-6 (IL6) and colony-stimulating factor 3 (CSF3). The osteogenic process was negatively affected by the inhibition of JAK/STAT3 signaling pathway.

CONCLUSIONS

This work might provide new insights in the crucial features of the transcriptional regulation during the osteogenesis, as well as offer important clues about the activity and regulation of the relatively long-activated Cytokine/JAK/STAT3 signaling pathway in osteoinduction of BMSCs.

The role of PIWI-interacting RNA in naringin pro-angiogenesis by targeting HUVECs

Angiogenesis is a biological process in which resting endothelial cells start proliferating, migrating and forming new blood vessels. Angiogenesis is particularly important in the repair of bone tissue defects. Naringin (NG) is the main active monomeric component of traditional Chinese medicine, which has various biological activities, such as anti-osteoporosis, anti-inflammatory, blood activation and microcirculation improvement. At present, the mechanism of naringin in the process of angiogenesis is not clear. PIWI protein-interacting RNA (piRNA) is a small noncoding RNA (sncRNA) that has the functions of regulating protein synthesis, regulating the structure of chromatin and the genome, stabilizing mRNA and others. Several studies have demonstrated that piRNAs can mediate the angiogenesis process. Whether naringin can interfere with the process of angiogenesis by regulating piRNAs and related target genes deserves further exploration. Thus, the purpose of this study was to validate the potential angiogenic and bone regeneration properties and related mechanisms of naringin both in vivo and in vitro.

Isopsoralen suppresses receptor activator of nuclear factor kappa-β ligand-induced osteoclastogenesis by inhibiting the NF-κB signaling

Osteoporosis is a serious systemic metabolic bone system disease.This study aimed to identify the target genes of isopsoralen and the signaling pathways involved in the differential expression of the genes involved in osteoclast differentiation. We hypothesized that isopsoralen may inhibit osteoclast differentiation by blocking the nuclear factor kappa-B (NF-κB) signaling pathway and verified our hypothesis through basic experiments. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to detect the effect of isopsoralen on the proliferation and viability of primary mouse bone marrow monocytes (BMMCs). The effect of isopsoralen on receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast differentiation was determined by using tartrate-resistant acid phosphatase (TRAP) staining. Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expression of the related genes and proteins. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway of isopsoralen target genes were obtained through comprehensive analysis using the STITCH database, Cytoscape 3.8.2, and R-Studio software. Differentially expressed genes (DEGs) were found in osteoclasts induced by RANKL before and after 3 days using R-Studio, following which KEGG analysis was performed. Next, enrichment analysis was performed on the KEGG pathway shared by the target genes of isopsoralen and the differentially expressed genes during osteoclast differentiation to predict the signaling pathway underlying the inhibition of osteoclast differentiation by isopsoralen. Finally, Western blot was used to detect the effect of isopsoralen on the activation of signaling pathways to verify the results of our bioinformatics analysis. Based on the enrichment analysis of isopsoralen target genes and differentially expressed genes during osteoclastogenesis, we believe that isopsoralen can inhibit RANKL-induced osteoclastogenesis by inhibiting the NF-κB signaling pathway.

Using network pharmacology and molecular docking verification to explore the mechanism of ursolic acid in the treatment of osteoporosis

Whether ursolic acid is an effective drug in treatment of osteoporosis (OP) and how it exhibit activity effect on OP is unclear. To investigated the potential molecular mechanism of ursolic acid in the treatment of OP and figured out its possible mechanism is necessary. The target genes of ursolic acid were screened by using the database of traditional chinese medicine systems pharmacology, PubMed database and UniProt database. OP-related target genes were searched by GeneCards database, and utilized online mapping tool to obtain common target genes of component-disease. String database was used to construct a protein-protein interaction (PPI) network of component-disease common target genes and perform topological analysis to screen core target genes. DAVID database was performed gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis for component-disease shared target genes. Using the core target protein as the receptor and ursolic acid as the ligand, the molecular docking was performed using AutoDockVina 1.1.2 software. A total of 52 ursolic acid-related target genes and 4657 OP-related target genes were excavated, with a total of collective 43 target genes. The above-mentioned PPI network with shared target genes contains 43 nodes and 510 edges, with an average node degree value of 23.32. A total of 24 core target genes were obtained, mainly including tumor protein p53 (TP53), vascular endothelial growth factor A (VEGFA), interleukin-6 (IL6), tumor necrosis factor (TNF), caspase3 (CASP3), matrix metallo protein (MMP9), transcription factor AP-1 (JUN), activator of transcription 3 (STAT3), mitogen-activated protein kinase 8 (MAPK8), and prostaglandin endoperoxidase 2 (PTGS2), respectively. According to KEGG enrichment analysis, there are 126 treatment of OP signaling pathway were enriched. GO enrichment analysis revealed that 313 biological processes were identified. The molecular docking result showed that the binding energies were all lower than -5 kcal/mol, indicating strong binding activity to the protein by the 6 core target gene. The therapeutic effect of ursolic acid on OP may be achieved by regulating TP53, JUN, IL6, VEGFA, CASP3, and MAPK8 genes, respectively. It exhibits possible biological function in the treatment of OP mainly involve positive regulation of apoptotic process, response to drug, incytoplasm, cytosol, protein binding, identical protein binding. Its mechanism may related to multiple therapeutic targets and signaling pathways such as cancer pathway, hepatitis B, and TNF signaling pathway.

Galangin induces the osteogenic differentiation of human amniotic mesenchymal stem cells via the JAK2/STAT3 signaling pathway

The regulation of stem cell directional differentiation is a core research topic in regenerative medicine, and modulating the fate of stem cells is a promising strategy for precise intervention through the utilization of naturally small molecule compounds. The present study aimed to explore the potential pro-osteogenic differentiation effect of galangin, a flavonoid derived from Alpinia officinarum, on human amniotic mesenchymal stem cells (hAMSCs) and the underlying molecular mechanism. The results showed that galangin had no cytotoxicity towards hAMSCs when the concentration was less than 50 μM. Treatment with 10 μM galangin significantly increased alkaline phosphatase (ALP) secretion and calcium deposition in hAMSCs. Meanwhile, galangin upregulated the mRNA and protein expression of early osteoblast-specific markers, namely ALP, RUNX2, and OSX, and late osteoblast-specific markers, CoL1α1, OPN, and OCN, in hAMSCs. Furthermore, signaling pathway screening studies showed that galangin enhanced the phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3). In addition, molecular docking results suggest there is a promising interaction between galangin and JAK2. Finally, treatment with the JAK2 specific inhibitor AG490 effectively reversed the induction of osteogenic differentiation, upregulation of osteoblast-specific marker expression, and activation of JAK2/STAT3 signaling induced by galangin. These results show that galangin induces the osteogenic differentiation of hAMSCs through the JAK2/STAT3 signaling pathway and could serve as a promising small molecular osteoinducer for application to hAMSCs in regenerative medicine.

Curcumin Prevents Diabetic Osteoporosis through Promoting Osteogenesis and Angiogenesis Coupling via NF-κB Signaling

Diabetic osteoporosis (DOP) is a metabolic disease which is characterized by impaired bone microarchitecture and reduced bone mineral density resulting from hyperglycemia. Curcumin, an effective component extracted from Curcuma longa, exhibits antioxidation, regulation of bone metabolism and hypoglycemic effects. The BMSC-mediated osteogenesis and angiogenesis coupling seems to be important in bone formation and regeneration. We aimed to explore the effect of curcumin on BMSC-mediated osteogenesis-angiogenesis coupling in high glucose conditions and underlying mechanisms. Our results showed that high glucose impaired the osteogenic and proangiogenic ability of BMSCs and that curcumin pretreatment rescued the BMSC dysfunction induced by high-concentration glucose. Inhibition of the high glucose-activated NF-κB signaling pathway has been found to contribute to the protective effects of curcumin on high glucose-inhibited coupling of osteogenesis and angiogenesis in BMSCs. Furthermore, accelerated bone loss and decreased type H vessels were observed in diabetic osteoporosis mice models. However, curcumin treatment prevented bone loss and promoted vessel formation in diabetic osteoporosis mice. Based on these results, we concluded that curcumin ameliorated diabetic osteoporosis by recovering the osteogenesis and angiogenesis coupling of BMSCs in hyperglycemia, partly through inhibiting the high glucose-activated NF-κB signaling pathway.

Effect and Related Mechanism of Platelet-Rich Plasma on the Osteogenic Differentiation of Human Adipose-Derived Stem Cells

Objective

Human adipose-derived stem cells (hADSCs) are ideal seed cells for the regeneration of alveolar bone defects. Platelet-rich plasma (PRP), which is rich in growth factors, promotes tissue repair. The purpose of the present study was to investigate whether PRP promotes the osteogenic differentiation of hADSCs and to perform high-throughput sequencing to explore the possible mechanism.

Methods

hADSCs were divided into the three following groups: CON group, OM group, and PRP group. Osteogenesis was detected by Alizarin Red staining on day 14. Total RNA was extracted from the OM and PRP groups for high-throughput sequencing. The target genes of the differentially expressed osteogenic-related miRNAs were predicted, and combined miRNA/mRNA analysis was then performed. The mRNA and protein expression levels of hsa-miR-212-5p, type 1 cannabinoid receptor (CNR1), alkaline phosphatase (ALP), Runx2, osteocalcin (OCN), and collagen 1 A1 (COL1A1) in the OM and PRP groups were detected by qRT–PCR and Western blot analyses. The binding between hsa-miR-212-5p and CNR1 was detected by a dual-luciferase reporter assay.

Results

Both the OM and PRP groups exhibited enhanced proliferation of hADSCs, and the differences at 48 h and 72 h were statistically significant (P < 0.05). The PRP group had significantly more calcium nodules than the CON group (P < 0.05). Through high-throughput sequencing analysis, differential miRNA and mRNA expression profiles were obtained. During hADSC osteogenesis, the expression of hsa-miR-212-5p was downregulated, and the expression of CNR1 was upregulated. hsa-miR-212-5p was found to bind directly to the 3′ UTR of CNR1.

Conclusions

The present findings indicated that downregulation of hsa-miR-212-5p and upregulation of CNR1 may be involved in the process by which PRP promotes the osteogenic differentiation of hADSCs.

STAT3-mediated osteogenesis and osteoclastogenesis in osteoporosis

Osteoporosis is a common skeletal disease with marked bone loss, deterioration of the bone microstructure and bone fragility. An abnormal bone remodelling cycle with relatively increased bone resorption is the crucial pathophysiological mechanism. Bone remodelling is predominantly controlled by osteoblasts and osteoclasts, which are specialized cell types that are regulated by a variety of osteogenic and osteoclastic factors, including cytokines expressed within the bone microenvironment under local or systemic inflammatory conditions. Signal transducer and activator of transcription 3 (STAT3) plays a prominent role in the communication between cytokines and kinases by binding downstream gene promotors and is involved in a wide range of biological or pathological processes. Emerging evidence suggests that STAT3 and its network participate in bone remodelling and the development of osteoporosis, and this factor may be a potent target for osteoporosis treatment. This review focuses on the role and molecular mechanism of the STAT3 signalling pathway in osteogenesis, osteoclastogenesis and osteoporosis, particularly the bone-related cytokines that regulate the osteoblastic differentiation of bone marrow stromal cells and the osteoclastic differentiation of bone marrow macrophages by initiating STAT3 signalling. This review also examines the cellular interactions among immune cells, haematopoietic cells and osteoblastic/osteoclastic cells.

Catalpol Enhances Random-Pattern Skin Flap Survival by Activating SIRT1-Mediated Enhancement of Autophagy

Random-pattern skin flap necrosis limits its application in the clinic. It is still a challenge for plastic surgeons. Catalpol is an effective ingredient extracted from Rehmannia glutinosa, which is reported to promote angiogenesis and protect against ischemic cerebral disease. The aim of our experiment is to assess whether catalpol can facilitate random flap survival and the underlying mechanisms. Male “McFarlane flap” rat models were employed to explore the protective effects of catalpol. The range of necrosis in the flap was calculated 7 days after the models were established. The flap specimens were harvested for further experiments, including angiogenesis, apoptosis, oxidative stress, and autophagy evaluation. Catalpol-treated group promoted the average survival area of the flap than that in the control group. Based on immunohistochemical staining, Western blotting, and ROS detection, we found that catalpol significantly reduces oxidative stress and apoptosis and increases angiogenesis. Hematoxylin and eosin (H&E) staining and laser Doppler images further clarified the enhancement of angiogenesis after catalpol treatment. The impact of catalpol in flap was switched by using 3-methyladenine (3MA), proving the important role of autophagy in curative effect of catalpol on skin flaps. Importantly, the ability of catalpol to regulate autophagy is mediated by the activation of sirtuin 1 (SIRT1) based on its high affinity for SIRT1. Our findings revealed that catalpol improved the viability of random skin flaps by activating SIRT1-mediated autophagy pathway.

Evolving Roles of Natural Terpenoids From Traditional Chinese Medicine in the Treatment of Osteoporosis

Osteoporosis (OP) is a systemic metabolic skeletal disease which can lead to reduction in bone mass and increased risk of bone fracture due to the microstructural degradation. Traditional Chinese medicine (TCM) has been applied in the prevention and treatment of osteoporosis for a long time. Terpenoids, a class of natural products that are rich in TCM, have been widely studied for their therapeutic efficacy on bone resorption, osteogenesis, and concomitant inflammation. Terpenoids can be classified in four categories by structures, monoterpenoids, sesquiterpenoids, diterpenoids, and triterpenoids. In this review, we comprehensively summarize all the currently known TCM-derived terpenoids in the treatment of OP. In addition, we discuss the possible mechanistic-of-actions of all four category terpenoids in anti-OP and assess their therapeutic potential for OP treatment.

Stat3 Signaling Pathway: A Future Therapeutic Target for Bone-Related Diseases

Signal transducer and activator of transcription 3 (Stat3) is activated by phosphorylation and translocated to the nucleus to participate in the transcriptional regulation of DNA. Increasing evidences point that aberrant activation or deletion of the Stat3 plays a critical role in a broad range of pathological processes including immune escape, tumorigenesis, and inflammation. In the bone microenvironment, Stat3 acts as a common downstream response protein for multiple cytokines and is engaged in the modulation of cellular proliferation and intercellular interactions. Stat3 has direct impacts on disease progression by regulating mesenchymal stem cells differentiation, osteoclast activation, macrophage polarization, angiogenesis, and cartilage degradation. Here, we describe the theoretical basis and key roles of Stat3 in different bone-related diseases in combination with in vitro experiments and animal models. Then, we summarize and categorize the drugs that target Stat3, providing potential therapeutic strategies for their use in bone-related diseases. In conclusion, Stat3 could be a future target for bone-related diseases.

A dual role of HIF1α in regulating osteogenesis–angiogenesis coupling

Objectives

The hypoxia-inducible factor 1-α (HIF1α), a key molecule in mediating bone-vessel crosstalk, has been considered a promising target for treating osteoporosis caused by gonadal hormones. However, senile osteoporosis, with accumulated senescent cells in aged bone, has a distinct pathogenesis. The study aimed at revealing the unknown role of HIF1α in aged bone, thus broadening its practical application in senile osteoporosis.

Materials and methods

Femurs and tibias were collected from untreated mice of various ages (2 months old, 10 months old, 18 months old) and treated mice (2 months old, 18 months old) underwent 4-w gavage of 2-methoxyestradiol (a kind of HIF1α inhibitor). Bone-vessel phenotypes were observed by microfil infusion, micro-CT and HE staining. Markers of senescence, osteogenesis, angiogenesis, oxidative stress and expression of HIF1α were detected by senescence β-galactosidase staining, qRT-PCR, western blot and immunostaining, respectively. Furthermore, bone mesenchymal stem cells from young mice (YBMSCs) and aged mice (ABMSCs) were transfected by knockout siRNA and overexpression plasmid of HIF1α. Senescence β-galactosidase staining, Cell Counting Kit-8, transwell assay, alkaline phosphatase staining, alizarin red-S staining and angiogenesis tests were utilized to assess the biological properties of two cell types. Then, Pifithrin-α and Nutlin-3a were adopted to intervene p53 of the two cells. Finally, H₂O₂ on YBMSCs and NAC on ABMSCs were exploited to change their status of oxidative stress to do a deeper detection.

Results

Senescent phenotypes, impaired osteogenesis–angiogenesis coupling and increased HIF1α were observed in aged bone and ABMSCs. However, 2-methoxyestradiol improved bone-vessel metabolism of aged mice while damaged that of young mice. Mechanically, HIF1α showed opposed effects in regulating the cell migration and osteogenesis–angiogenesis coupling of YBMSCs and ABMSCs, but no remarked effect on the proliferation of either cell type. Pifithrin-α upregulated the osteogenic and angiogenic markers of HIF1α-siRNA-transfected YBMSCs, and Nutlin-3a alleviated those of HIF1α-siRNA-transfected ABMSCs. The HIF1α-p53 relationship was negative in YBMSCs and NAC-treated ABMSCs, but positive in ABMSCs and H₂O₂-treated YBMSCs.

Conclusion

The dual role of HIF1α in osteogenesis–angiogenesis coupling may depend on the ROS-mediated HIF1α-p53 relationship. New awareness about HIF1α will be conducive to its future application in senile osteoporosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02742-1.

Osteoinductive activity of bisdemethoxycurcumin and its synergistic protective effect with human amniotic mesenchymal stem cells against ovariectomy-induced osteoporosis mouse model

Osteoporosis is a common disease characterized by skeletal fragility and microarchitectural deterioration. However, existing conventional drugs exhibit limited efficacy and can elicit severe adverse effects; moreover, and novel stem cell-based therapies have not exhibited sufficient therapeutic efficacy. Our hypothesis is that an appropriate osteogenic inducer may improve their therapeutic efficacy. In this study, we found that bisdemethoxycurcumin (BDMC) stimulates the differentiation of human amniotic mesenchymal stem cells (hAMSCs) into osteoblasts without inducing cytotoxicity. Here BDMC enhances calcium deposition in hAMSCs, while promoting the expression of early and late markers of osteoblast differentiation, including ALP, runt-related transcription factor 2, osterix, COL1-α1, osteocalcin, and osteopontin at the transcriptional and translational levels. Mechanistically, BDMC was found to activate the JAK2/STAT3 pathway; whereas AG490 (JAK2/STAT3 pathway inhibitor) inhibited BDMC functioning. Subsequently, we found that the combinatorial therapy of BDMC and hAMSC had a positive synergistic effect on osteoporotic mouse model induced by bilateral ovariectomy, including inhibiting bone loss and bone resorption and improving bone micro-architecture. Moreover, BDMC inhibited production of the bone resorption markers C-terminal telopeptide of type I collagen, and tartrate resistant acid phosphatase, while promoting serum levels of bone formation markers OCN, and procollagen I N-terminal propeptide. BDMC also improved liver and kidney function in osteoporotic mouse model. Collectively, BDMC improved osteoporosis by enhancing hAMSC osteogenesis and exhibited a protective effect on liver and kidney function in an osteoporotic mouse model. Hence, BDMC may serve as an effective adjuvant, and combined therapy with hAMSCs is a promising new approach toward osteoporosis treatment.

Circ_0019693 promotes osteogenic differentiation of bone marrow mesenchymal stem cell and enhances osteogenesis-coupled angiogenesis via regulating microRNA-942-5p-targeted purkinje cell protein 4 in the development of osteoporosis

Circular RNA (circRNA) is a crucial regulator in multiple human diseases, including osteoporosis (OP). However, the function of numerous circRNAs remains unclear. This study aimed to explore the role and mechanism of circ_0019693 in bone marrow mesenchymal stem cell (BMSC) osteogenic differentiation and osteogenesis-coupled angiogenesis. The expression of circ_0019693, miR-942-5p and purkinje cell protein 4 (PCP4) was measured using quantitative real-time PCR (qPCR) or Western blot. Osteogenic differentiation was monitored according to the protein levels of RUNX family transcription factor 2 (RUNX2), osteopontin (OPN) and osteocalcin (OCN) by Western blot analysis, and the activity of alkaline phosphatase (ALP). Angiogenesis was evaluated by tube formation assay. The targeting relationship between miR-942-5p and circ_0019693 or PCP4 was identified using pull-down, dual-luciferase reporter, and RNA immunoprecipitation assays. Circ_0019693 was downregulated in serum samples and bone tissues from OP patients relative to normal subjects. Circ_0019693 expression was enhanced in the stages of BMSC osteogenic differentiation. Circ_0019693 overexpression enhanced the activity of ALP and the expression of RUNX2, OPN and OCN, and its overexpression also promoted angiogenesis. However, circ_0019693 knockdown played the opposite effects. MiR-942-5p was ensured to be a target of circ_0019693, and miR-942-5p enrichment reversed the effects of circ_0019693. In addition, PCP4 was a target of miR-942-5p, and miR-942-5p inhibitor-promoted BMSC osteogenic differentiation and angiogenesis were partly repressed by PCP4 knockdown. In conclusion, circ_0019693 promotes BMSC osteogenic differentiation osteogenesis-coupled angiogenesis via regulating miR-942-5p-targeted PCP4, thus blocking the development of OP.

Hydrogel contained valproic acid accelerates bone-defect repair via activating Notch signaling pathway in ovariectomized rats

The purpose was to observe whether valproic acid (VPA) has a positive effect on bone-defect repair via activating the Notch signaling pathway in an OVX rat model. The MC3T3-E1 cells were cocultured with VPA and induced to osteogenesis, and the osteogenic activity was observed by alkaline phosphatase (ALP) staining, Alizarin Red (RES) staining and Western blotting (WB). Then the hydrogel-containing VPA was implanted into the femoral epiphysis bone-defect model of ovariectomized (OVX) rats for 12 weeks. Micro-CT, biomechanical testing, histology, immunofluorescence, RT-qPCR, and WB analysis were used to observe the therapeutic effect and explore the possible mechanism. ALP and ARS staining and WB results show that the cell mineralization, osteogenic activity, and protein expression of ALP, OPN, RUNX-2, OC, Notch 1, HES1, HEY1, and JAG1 of VPA group is significantly higher than the control group. Micro-CT, biomechanical testing, histology, immunofluorescence, and RT-qPCR evaluation show that group VPA presented the stronger effect on bone strength, bone regeneration, bone mineralization, higher expression of VEGFA, BMP-2, ALP, OPN, RUNX-2, OC, Notch 1, HES1, HEY1, and JAG1 of VPA when compared with OVX group. Our current study demonstrated that local treatment with VPA could stimulate repair of femoral condyle defects, and these effects may be achieved by activating Notch signaling pathway and acceleration of blood vessel and bone formation.

CaMKII inhibitor KN-93 impaired angiogenesis and aggravated cardiac remodelling and heart failure via inhibiting NOX2/mtROS/p-VEGFR2 and STAT3 pathways

Persistent cardiac Ca²⁺/calmodulin‐dependent Kinase II (CaMKII) activation was considered to promote heart failure (HF) development, some studies believed that CaMKII was a target for therapy of HF. However, CaMKII was an important mediator for the ischaemia‐induced coronary angiogenesis, and new evidence confirmed that angiogenesis inhibited cardiac remodelling and improved heart function, and some conditions which impaired angiogenesis aggravated ventricular remodelling. This study aimed to investigate the roles and the underlying mechanisms of CaMKII inhibitor in cardiac remodelling. First, we induced cardiac remodelling rat model by ISO, pre‐treated by CaMKII inhibitor KN‐93, evaluated heart function by echocardiography measurements, and performed HE staining, Masson staining, Tunel staining, Western blot and RT‐PCR to test cardiac remodelling and myocardial microvessel density; we also observed ultrastructure of cardiac tissue with transmission electron microscope. Second, we cultured HUVECs, pre‐treated by ISO and KN‐93, detected cell proliferation, migration, tubule formation and apoptosis, and carried out Western blot to determine the expression of NOX2, NOX4, VEGF, VEGFR2, p‐VEGFR2 and STAT3; mtROS level was also measured. In vivo, we found KN‐93 severely reduced myocardial microvessel density, caused apoptosis of vascular endothelial cells, enhanced cardiac hypertrophy, myocardial apoptosis, collagen deposition, aggravated the deterioration of myocardial ultrastructure and heart function. In vitro, KN‐93 inhibited HUVECs proliferation, migration and tubule formation, and promoted apoptosis of HUVECs. The expression of NOX2, NOX4, p‐VEGFR2 and STAT3 were down‐regulated by KN‐93; mtROS level was severely reduced by KN‐93. We concluded that KN‐93 impaired angiogenesis and aggravated cardiac remodelling and heart failure via inhibiting NOX2/mtROS/p‐VEGFR2 and STAT3 pathways.

PPARβ/δ accelerates bone regeneration in diabetic mellitus by enhancing AMPK/mTOR pathway-mediated autophagy

BACKGROUND

Diabetic patients are more vulnerable to skeletal complications. Peroxisome proliferators-activated receptor (PPAR) β/δ has a positive regulatory effect on bone turnover under physiologic glucose concentration; however, the regulatory effect in diabetes mellitus has not been investigated yet. Herein, we explored the effects of PPARβ/δ agonist on the regeneration of diabetic bone defects and the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) under a pathological high-glucose condition.

METHODS

We detected the effect of PPARβ/δ agonist on osteogenic differentiation of rBMSCs in vitro and investigated the bone healing process in diabetic rats after PPARβ/δ agonist treatment in vivo. RNA sequencing was performed to detect the differentially expressed genes and enriched pathways. Western blot was performed to detect the autophagy-related protein level. Laser confocal microscope (LSCM) and transmission electron microscope (TEM) were used to observe the formation of autophagosomes.

RESULTS

Our results demonstrated that the activation of PPARβ/δ can improve the osteogenic differentiation of rBMSCs in high-glucose condition and promote the bone regeneration of calvarial defects in diabetic rats, while the inhibition of PPARβ/δ alleviated the osteogenic differentiation of rBMSCs. Mechanistically, the activation of PPARβ/δ up-regulates AMPK phosphorylation, yielding mTOR suppression and resulting in enhanced autophagy activity, which further promotes the osteogenic differentiation of rBMSCs in high-glucose condition. The addition of AMPK inhibitor Compound C or autophagy inhibitor 3-MA inhibited the osteogenesis of rBMSCs in high-glucose condition, suggesting that PPARβ/δ agonist promotes osteogenic differentiation of rBMSCs through AMPK/mTOR-regulated autophagy.

CONCLUSION

In conclusion, our study demonstrates the potential role of PPARβ/δ as a molecular target for the treatment of impaired bone quality and delayed bone healing in diabetic patients for the first time.

TP53-mediated miR-2861 promotes osteogenic differentiation of BMSCs by targeting Smad7

Bone defect seriously affects the quality of life. Meanwhile, osteogenic differentiation in BMSCs could regulate the progression of bone defect. Transcription factors are known to regulate the osteogenic differentiation in BMSCs. The study aimed to investigate the detailed mechanism by which TP53 regulates the osteogenic differentiation. To study bone defect in vitro, BMSCs were isolated from spinal cord injury rats. CCK-8 assay was applied to test the cell viability. The mineralized nodules in BMSCs was tested by alizarin red staining. Meanwhile, TUNEL staining and flow cytometry were performed to test the cell apoptosis. mRNA expression was tested by qRT-PCR. Starbase and dual-luciferase reporter assay were used to predict the downstream mRNA of miR-2861. Moreover, western blot was applied to detect the protein expressions (TP53 and Smad7). BMSCs were successfully isolated from rats. The expressions of miR-2861 were significantly upregulated in osteogenic medium, compared with growth medium. MiR-2861 inhibitor significantly decreased the levels of OCN, ALP, BSP, and Runx2 in BMSCs. In addition, miR-2861 inhibitor notably inhibited the mineralized nodules, viability, and induced the apoptosis of BMSCs. Smad7 was identified to be the downstream target of miR-2861, and knockdown of Smad7 notably reversed miR-2861 inhibitor-induced inhibition of osteogenic differentiation and promotion of apoptosis in BMSCs. Moreover, miR-2861 was transcriptionally regulated by TP53 in BMSCs. TP53-meidiated miR-2861 promotes osteogenic differentiation of BMSCs by targeting Smad7. Thereby, our research might provide new methods for bone defect treatment.

Integrating Bioinformatic Strategies with Real-World Data to Infer Distinctive Immunocyte Infiltration Landscape and Immunologically Relevant Transcriptome Fingerprints in Ossification of Ligamentum Flavum

Purpose

Ossification of the ligamentum flavum (OLF) is a multifactorial disease characterized by an insidious and debilitating process of abnormal bone formation in ligamentum tissues. However, its definite pathogenesis has not been fully elucidated. Potential links between the immune system and various forms of heterotopic ossification have been discussed for many years, whereas no research investigated the immune effects on the initiation and development of OLF. Therefore, we attempt to shed light on this issue.

Methods

A series of bioinformatic algorithms were integrated to evaluate the immune score and the immunocyte infiltration patterns between OLF and normal samples, screen OLF-related and immune-related differentially expressed genes (OIDEGs), and analyze their biological functions. Correlation analysis inferred OIDEGs-related differentially expressed lncRNAs (OIDELs) and infiltrating immune cells (OIICs) to construct an immunoregulatory network.

Results

Differential immune score and immune cell infiltration were determined between two groups, and 10 OIDEGs with diverse biological function annotations were identified and verified. A lncRNA-gene-immunocyte regulatory network further revealed 10 OIDEGs, 41 OIDELs and 7 OIICs that were highly correlated. Among them, CD1E and STAT3 were predicted as hub genes whether at the expression level or interaction level. cDCs emerged as having the most prominent differences and the highest degree of connectivity. FO393414.3, AC096734.1, LINC01137 and DLX6-AS1 with the greatest number of OIDEGs were thought to be more likely to participate in immunoregulation of OLF.

Conclusion

This is the first research to preliminarily elucidate OLF-related immunocyte infiltration landscape and immune-associated transcriptome signatures based on bioinformatic strategies and real-world data, which may provide compelling insights into the pathogenesis and therapeutic targets of OLF.